What causes a sacral dimple?

Sacral dimples are minor congenital anomalies -unusual anatomic features of no serious consequence- with no known cause. In rare cases associated with serious underlying abnormalities of the spine or spinal cord -such as spina bifia and tethered cord syndrome- they may be marked by a skin tag or skin discoloration.

Sacral dimples are especially common among infants and young children and occur in roughly 3 to 8 percent of children, according to health experts at PediatricEducation.org. While most sacral dimples get smaller with age or go away entirely on their own, observed swelling, redness, fluid draining or tenderness requires medical attention.